Use HHVM to speed up Composer

The new and ultra fast HHVM compiler for PHP is out for some time now. The guys at Facebook are doing great work and really making progress. Now they pass tests with 100% for a growing number of frameworks, with Laravel being one of the first few.

At this moment I wouldn't recommend to use HHVM on a production server. You can use it in a
fastcgi mode which works the same way as PHP-FPM, but it's a little to early for that to use on your precious websites and applications.